What is OpenCode? The open source coding agent in plain words

What is OpenCode? It is an open source AI coding agent: you describe a task in plain English, and it reads your project, edits files and runs commands to get the task done. The app is free, MIT licensed and made by a company called Anomaly, and it can work with models from Anthropic, OpenAI, Google, your own computer and dozens of other providers.

Everything below comes from the OpenCode website and its docs, as of November 2026.

The answer in five lines

• What it is: an agent that writes and changes code for you, with your permission.
• Where it runs: a full-screen terminal interface, a desktop app for macOS, Windows and Linux, and a web interface.
• Which AI it uses: whichever you connect. The catalog spans more than 75 providers, and local models work too.
• What it costs: the software is free. Paid models cost whatever their provider or OpenCode's own services charge.
• Who makes it: Anomaly, with the source code public on GitHub.

How a session works

You open a terminal in a project folder and type opencode. The first time, /connect asks which provider to use, and /models picks the model. From there you chat with it like you would brief a colleague.

OpenCode has two main modes. Plan looks through the code and proposes an approach without editing your project. Build is the default and actually makes the changes. A sensible habit is to plan first, read the proposal, then let Build carry it out. For scripts, opencode run "your prompt" returns an answer without the interactive screen.

Why people pick it

The main draw is freedom of model. You can try a cheap open-weight model for routine fixes and a stronger paid one for hard bugs, all in the same tool. You can also sign in with a ChatGPT Plus, ChatGPT Pro or GitHub Copilot account you already have, instead of buying another subscription.

The second draw is privacy. OpenCode says it does not store your code or context data, and that data is only kept when you use its free models. Its repository has more than 220,000 stars on GitHub, which shows how many developers follow it.

Who it is not for

If you want suggestions while you type inside an editor, an autocomplete assistant is a simpler fit. And if you already pay for one vendor's plan that bundles its own coding agent, that agent may cover you without extra setup.

How to keep an eye on what it uses

Because OpenCode can talk to several providers, your spending gets spread over several bills. OpenCode does keep a local record of tokens and sessions, and the simplest way to read it is UsageAtlas, a free and open source desktop app. Run it on the same computer and it lists your OpenCode tokens, requests, models and sessions, with an estimated cost, next to any other coding tools you use such as Claude Code or Cursor.

It works without an account and never reads your prompts or the replies. The figures are estimates, so the provider's own invoice stays the record of what you paid.